Basically, the liquid crystal display device is constituted by a light source device, and a liquid crystal display element. As the light source device, an edge light type backlight (backlight source device) has been frequently used from the viewpoint of a reduction in size of the liquid crystal display device. In the edge light type backlight, at least one side end surface of a rectangular plate-shaped light guide is used as a light incident end surface, and a linear or rod-shaped primary light source such as a straight pipe type fluorescent lamp or a spot-shaped primary light source such as a light emitting diode (LED) is disposed along the light incident end surface. Light generated from the primary light source is allowed to be incident to the light incident end surface of the light guide, is guided to the inside of the light guide, and is emitted from a light emitting surface that is one surface of two main surface of the light guide. The light emitted from the light emitting surface of the light guide is diffused by a light diffusion element such as a light diffusion film that is disposed on the light emitting surface, and is deflected to a necessary direction by a light deflection element such as a prism sheet. Light is also emitted from a rear surface that is a main surface opposite to the light emitting surface of the light guide, and a light reflection element such as a light reflection sheet is disposed to face the rear surface so as to return the light to the light guide.
As the above-described light guide, a light guide, which is obtained by forming various optical functional structures in a thermoplastic resin shaped-article that is a material of the light guide, can be used. Examples of the optical functional structure include a light emission mechanism configured to emit light that is guided to the inside of the light guide.
As the light emission mechanism, there is disclosed a method of using bubbles which are formed by application of radiation energy and thermal energy (for example, refer to Patent Document 1).